Neurological disorders such as Parkinson's disease can be a chronic, progressive neurodegenerative movement disorder whose primary symptoms include tremors, rigidity, slow movement, poor balance and difficulty walking and in speech. When a person has Parkinson's disease, his/her dopamine-producing cells in the brain begin to die. Dopamine is responsible for sending information to the parts of the brain that control movement and coordination. Hence, as the amount of dopamine produced decreases, messages from the brain directing the body how and when to move are delivered in a slower fashion, leaving a person incapable of initiating and controlling movements in a normal way.
Deep Brain Stimulation (DBS) is a surgical therapy for movement disorders that represents an advancement in the treatment of Parkinson over the last 50 years. DBS uses a surgically implanted, battery-operated thin neuron-stimulator to reverse in large part the abnormal function of the brain tissue in the region of the stimulating electrode.
Commercially available DBS systems typically include a neuron-stimulator, an extension, and a lead. The neuron-stimulator is placed under skin operating as a battery powered electrical impulse generator implanted in the abdomen. The extension is a wire also placed under the skin (from the head, down the neck, to the abdomen) to bring the signals generated by neuron-stimulator to the lead. The lead is an insulated coiled wire with four electrodes implanted deeply in the brain to release the electrical impulse. Presently DBS devices operate only in open loop, namely, they are not continuously responsive to patient's status at a given instance of time but are fixed once the DBS electrodes are surgically implanted.
Innovative Aspects of the Present Invention
Achieving closed-loop control of DBS where control is continuously responsive to measurements at any given time, using noninvasive surface EMG sensors which sense integrated motor-neuron activity in the vicinity of the electrode through the skin (say, at muscles and limbs including facial muscles, fingers, and vocal cord) and/or implanted sensors.
In preferred realizations of this invention, processing of the data obtained from said sensors and the resulting control decision and control command signals are also performed in a noninvasive manner, these control commands being transmitted by wireless to the implanted device.
In some realization of this invention, measurements of patient's status are solely obtained from sensors that are noninvasive.
In preferred realizations of the present invention, signal processing involves prediction of time of next tremor and detecting and subsequent filtering out of desirable movements.
In realizations as in, sensing and control are then applicable to most existing DBS systems and do not require redesign of presently implanted DBS systems except for installing a miniature wireless receiver.
In some realizations, the stimulating electrode serves also as a sensing electrode, as is accomplished via electronic switching of connection and of impedance, to eliminate need for a separately implanted sensing electrode in the stimulated site of the patient's brain.